Air mandrel

ABSTRACT

An expansible mandrel is provided with a splined hollow shaft having perforations and connected to a source of compressed air. Around the shaft is an elastomeric sleeve, notched where it crosses a spline, which when air is introduced between the splines, expands, gripping any tube, such as the tube on which a roll of paper is wound. As the splined shaft is connected to the caps at both ends of the elastomeric sleeve, the latter is not subjected to torsional strains in use.

United States Patent [56] References Cited UNITED STATES PATENTS l,975,743 l0/l934 Gollong........

[72] Inventor Arnold G.Peterson Sunderland, Mass. Appl. No. 885,905

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[22] Filed Dec. 17.1969

[451 Patented Aug. 3, 1971 [73] Assignee J. P. Stevens 8: Co., Inc.

New York, N.Y.

ABSTRACT: An ex'pansible mandrel is provided with a splined hollow shaft having perforations and connected to a source of compressed air. Around the shaft is an elastomeric sleeve, notched where it crosses a spline, which when air is introduced between the splines, expands, gripping any tube, such as the tube on which a roll of paper is wound. As the splined shaft is connected to the caps at both ends of the elasto'meric sleeve, the latter is not subjected to torsional e s u. .m S .m m s 2 0. 2 2 76MB 8 umy n 427 24 h h546 6 4 B 2 n 6 u 4 "2 m7 m2 m7 m m m L m m u m h D R m A m m n R M S in I. s n k A4U I F 1 l l l 4 2 l 0 s 5 5 5 l l .l

PATENTED AUG 3:911

5% -i l- N. llll a zwmw E ill w m lkw. IHHWMP k N m 4 mN I N VEN TOR ARNOLD 6' PETERSON ATTORNEY muMV AIR MANDREL BACKGROUND OF THE INVENTION Expansible mandrels are known, for example, one in which SUMMARY OF THE INVENTION According to the present. invention an expansible mandrel comprises a hollow shaft with splines surrounded with an elastomeric sleeve, sealed at both ends, the sleeve being notched internally where it crossesa spline. When compressed air is introduced through perforations in they hollow shaft at.

one or more positions, the elastomeric sleeve expands but.

does not move far enough so that. the notched portions expand beyond the splines. In other words, even when. expanded a portion of the shoulder of each notch is inv contact with the spline and therefore transmits-drivingforce andv eliminates tor-- sional stresses in thesleeve. Sincethe splined hollow shaft or tube is locked to the drivingendcaps,it transmits the torsional. strain through the shoulders of the. notches of the elastomeric. sleeve, as has been described. Asthere are no. torsional strains. on the sleeve itself it cannot twistandhasa longzlife as com.- paredto sleeves which are attachedonlyonthe ends to driving caps. Long life is assured, andrequirements for air. pressureare at a minimum because theair. pressuremerely is required.

to bring the portions of the elastomericsleeve into contact. with the tube of a paper roll or othermaterial to bedriven.

BRIEF DESCRIPTION OF'TI-IE, DRAWINGS FIG. I is a longitudinal elevationof the hollow shaftand the elastomeric sleeve;

FIG. 2 is a section throughthecentral shaft alongthe line; 2-2, and FIG. 3 is a cross sectionthrough .the mandrel along theline- 3-3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the hollow shaftzl; which is connected to a source of compressed air. Attached-to the shaft are two caps 2? and 3 locked to the shaft I .by therecessed headscrews .1 land.

between which caps anv elastomeric sleeve 4 of polyurethane? extends. A splined shaft l2 with splines 5 is locked to the drivingcaps 2 and 3 by a threaded connection 9. The splinedshaft 12is spaced slightly from the-hollow shaft 1 and both shafts are Provided with perforations-6, atom or more positions, through which compressed air fromthe hollow shaft can flow. Hermetic sealing between the .two. shafts is provided b'y-the 0-- is, of course, repeated at the othenend at cap};

The sleeve 4 extends the full length between caps and where it passes over the splines is notched, as canbe bestseen'in FIG. 3. The portions of the sleeve between splines are substantially in contact with the surfaceof the splined shaftl2, as can'beseen in FIG. 2; When, however, compressed air is introduced, it passes out through the perforations 6 andcausesthe sleeve 4 to expand slightly, gripping atube -10 which'is to be .driven. In FIG. 3this tube is typically shown as being. a. center tube of a roll of paper, which is indicated at one side diagrammatically. FIG. 3 exaggerates somewhatthe height-of i 2 the splines 5 as compared to the diameterpf the shaft 12. Typically the splines may extend about one-fourth of an inch and when compressed air is introduced the sleeve moves up a much smaller amount, for example one-sixteenth of an inch. This results in' the shoulders of the notches in the sleeve 4 still contacting the splines through most of the spline height, as is shown in FIG. 3. While spline height is exaggerated in comparison to spline diameter in this figure, the relative size of splines and amount by which the sleeve 4 is expanded are substantially in proportion. As the shoulders of the notches inthe polyurethane sleeve 4 are incontact with the edges of the splines 5, torsional drive is transmitted by the splines, which extend the full length of the shaft-,and there is no torsional stress in the sleeve 4 whichwould cause it to twist, as was the case in prior constructions. Minimum air pressure can be used asit performs no function of stiffening the sleeve against tor slon.

FIG. 3 shows the paper tube 10, on which a roll of paper is wound, as being in contact with and tightly gripped by the polyurethane sleeve 4 when it is-expanded as shown in FIG; 3. When there is no pressure, the approximate one-sixteenth of an inch of expansion of the sleeve is not present, and this pro-' vides sufficient clearance so' that in the unexpanded condition the mandrel can be slid through a tube to be driven or the tube slid'over the mandrel, depending. on the construction of the driving elements of the mandrel, which are not shown as they are not changed by thepresent invention.

At the caps the. polyurethane sleeve is cast'into the grooves 8, which provides'for sealingagainst escapeof compressed air through thecaps. It is possible to formthe hollow inner shaft 1 with an enlarged splined portion, but the provision of a separatesplined shaft'surrounding it'with suitable perforations" is simpler and provides .driveof'the splined shaft through the 3V caps and so is preferred. As far as the expansion of the polyurethane sleeve4 is concerned, it makes no difference whether form the new function of the present'inventioneliminating torsional stresses on the polyurethane sleeve.

In the drawings a number: of holes'are shown in boththe central shaftand the splined 'shaft'. This-represents amore 'or less ideal construction because, of course, the'more holes' thereare the more uniform the air-pressure is. However, asfar as. connection between the hollow central shaft and the splined shaft-12,- even a single hole: can be' use'd'as the com"-' pressedair distributes itself betweenthe two shafts. Similarly, only a single set of radial holes are neededin the splined shaft 12; There must, of course, b'e-a-hol'e'between each pairof splines in order to force the polyurethane sleeve 4 out uniformly-when compressed air is applied." The airdistributes itself longitudinally alongthe splined'shaft between'th'e splines even if there is only one holebetween each pair of splines; The

drawings, however, show a more 'ideal arrangement with 'a b. caps surrounding. the hollow shaft and locked to the splined portion,.

0. an elastomeric sleeve surroundingthesplined portion-of the shaft and hermetically sealed to the caps,"

d. means for introducing-a compressed gas into the hollow" pressed air is introduced into the shaft, whereby when the-"- sleeve is expanded torsional drive 'is taken from the splines to the notches thereof.

2. An expansible mandrel according'to claim 1 in which a' hollow'perforated shaft is inside the'splined shaft,'the means for applying compressed gas being to the'central hollow shaft and the central'shaft-being'locked to the caps, which in turn are locked to the hollow splined shaft. whereby both shafts with the caps constitute a unit.

3. An expansible mandrel according to claim 2 in which the 

1. An expansible mandrel comprising in combination, a. a hollow splined shaft with perforations between splines, b. caps surrounding the hollow shaft and locked to the splined portion, c. an elastomeric sleeve surrounding the splined portion of the shaft and hermetically sealed to the caps, d. means for introducing a compressed gas into the hollow shaft, and e. the elastomeric sleeve surrounding the shaft being notched over the splines, the spline height being greater than expansion of the elastomeric sleeve when compressed air is introduced into the shaft, whereby when the sleeve is expanded torsional drive is taken from the splines to the notches thereof.
 2. An expansible mandrel according to claim 1 in which a hollow perforated shaft is inside the splined shaft, the means for applying compressed gas being to the central hollow shaft and the central shaft being locked to the caps, which in turn are locked to the hollow splined shaft, whereby both shafts with the caps constitute a unit.
 3. An expansible mandrel according to claim 2 in which the elastomeric sleeve is of polyurethane.
 4. An expansible mandrel according to claim 1 in which the elastomeric sleeve is of polyurethane. 